Power semiconductor modules are until now typically formed by multiple transitions from solder, adhesive, LTB (low temperature bonding), or a permanently flexible thermal-conduction paste that connects the constituent elements like cooling body, heat sink (base plate), substrate, and semiconductor with each other. In the process the semiconductors have to be soldered onto the substrate that mostly consists of several (insulating and metallic) layers, the substrate in turn has to be soldered onto a metal heat sink that, conducting well thermally (and mostly also electrically), represents the heat spreader and finally this heat spreader has to be connected to a cooling body. It is important that the high currents or electrical voltages that are used to operate the power semiconductors cannot reach the cooling body. It is therefore important to create a safe electric insulation and still to ensure a good heat transfer. The substrate is therefore conventionally formed as a thick-layer substrate, DCB or the like, where a ceramic core, e.g. Al2O3 or AlN or the like as an insulator with good thermal conduction is provided with two structured electrically conducting layers that consist, for example, of copper or thick film pastes. A problem with this type of structure is that the considerable amounts of heat are conducted through one or more transitions of solder or adhesive that embrittle by aging; the heat flow then has to be conducted through cross-sections that are correspondingly smaller and then age even faster.
Rigid power modules are protected against the influence of time and ageing by encapsulation. A method for manufacturing a rigid power module is for example already known from DE 10 2007 020 618 B3 by the applicant, where a compression mould is used to form a mould compound around a lead frame (fixed in the compression mould by a mounting die in the compression mould) in the populated state, during the forming process recesses remain at pre-determined positions and webs of the lead frame can be removed later by the punch that is inserted in the recesses.
The applicant's DE 10 2004 055 534 A1 already discloses a power semiconductor module whose construction is known having a sprayed-on layer of particles that are fused together as an electrically conducting wiring plane, intimately connected with this layer, on the sprayed-on layer. With this module a rigid ceramic substrate is replaced by a metallization. Therefore a solution is sought only for the inside of a module.